Telephone system.



F. W. DUNBAR, TELEPHONE SYSTEM.

APPLSCATION FlLED lAN.2\. HHS.

atontvd .huw 18, 1918.

FRANCIS W. DUNIBAR, 0F MANCHESTER, -VllllitlVOlQ'T, ASSIGNOR TO KELLOGGSWITCHBOARD AND-SUPPLY COMPANY, OF CHICAGO, ILLINOIS, .A CORPORA- TIONOF ILLINOIS.

TELEPHONE srsrnivr.vr

Patented June 18, 1918i.

Original application led March 3, 1905, Serial N o. 248,242. Divided andthis application led January 21,

To all lwhom t may concern:

Be it known that ,1, FRANCIS W. DUNBAR, a citizen of the UnitedStates ofAmerica, residing in Manchester, county of Bennington, State of Vermont,have invented certain new and useful vImprovements in Telephone Systems,of which the following is a specification. J n

My invention relatesvto telephone systems and has to do moreparticularlywith systems of the type inwlich automatic switching devices are usedinY completing connections between subscribers lines.

' The presentapplication is a divisional application of my applicationfor Letters Patent, Serial No. 248,242, filed March 3, 1905.

Themain object of my invention is to provide means for distributingcalls4 from calling subscribers lines to idle link circuits by means ofsuccessively operated automatic distributing devices. By usin aplurality of automatic devices successive y operable to connect acalling line to an idle link circuit, it will be readily seen that anyone calling line is given access to a greater number of link circuits ortrunks than if only one automatic switch was used to connect the*vcalling line to a link circuit.

Other objects and features of my system will lbe hereinafter pointed outin 'the following speciiication and in the appended claims. a'

1 will explain my -invention more fully by reference to the accompanyingdrawing, in whichf The drawing illustrates the adaptability of theinvention to one well known type of multiple switchboard, the invention,however, not being limited to multiple switchboard practice.

Each subscribers station,vA, B, is'provided with customary commonbattery sub scribers apparatus, a switch hook at leach station servingoperatively metallically to unite the sides of the line when the'receiver' 'is removed. I do not deem a detailed de# scription of thesubscribers apparatus to be essential, as the illustration is sufficientto make the same understood by those skilled in the art. Although I haveillustrated one arrangement of subscribers station apparatus, it will beobvious to those skilled in the art, thatother arrangements may be'employed at the substations, and 1 do not Serial No. 212,920.

apparatus shown, nor do I wish to be lim? ited in all embodiments of theinvention to. its application to a common battery system. Thesubscribers ,lines are` metallic lines (though the invention need not belimited to metallic circuits), said lines extending in two branches tothe exchange, where they terminate in normal contacts 1-2 normallyengaged by the armatures 11-21 of a cut-off relay 3. The contacts 1-2are preferably in the form of spring arms that are adapted to engagecontacts 12-13 when the armatures of said relay are attracted, suchconnection being broken when said armatures 11-21 are released.y Thecontacts 12-13A constitute the terminals of the oliice and of the line,which is' supplied with the; line jack 4:1. The system illustratedAbeing a multiple switchboard system, there are also provided upon othersections ofV the board than where jack 4 is located, other jacks 41 insimilar connection with the contactsl tonsmS, which Contact button 7being connected with a link circuit selector switch element, has arotating arm 9 connected thereto, there bein one such arm 9 for eachbutton 7, while t e contact buttons 8.are similarly connected with arms10 similar to the armsv.' Certain local control to be' hereinafterspecified, is obtained by the brush or contact 11. The activecontacts`11-5-6 all move together. The brush 11 rides over contacts 12, each.preferably connected with a rotating arm 13. All of the link circuits atan operators position are in association with the arms 9, 10 and 13, thev talking strands of said link circuits terminating;v in contact buttons14-15 engaged by the arms`9-10, respectively, while local circuitconductors associated with said link circuits are provided with Contactbuttons 16l engaged by the arin 13. When the 'brushes 5, 6 and 11 stopatone-set of contactsincluding a button 7, a button 8, and

,a button 12, they are then adapted'to effect a signal at a freeoperators position, and in the preferred embodiment of the invention,are adapted automatically to be connected with a link circuitcorresponding to said signal, there being desirably as many signalsas'there are link circuits.

In the system shown in the accompanying drawing, the link circuitterminates at one end in the contacts 16-14-15 and at the other endvin aconnecting plug, the arms 9-10-13 automatically selecting the linkcircuit in a manner to be hereinafter specified, the signalcorresponding'to said link circuit -thereupon being effected, so thatthe 20' operator thereupon uses the connecting plug 17 corresponding tothe signal.

Each line of a group of.. subscribers lines has as many buttons 7 asmany buttons 8, and as many buttons 12, as there areoperators4 assignedor corresponding to such group. Each subscriber has thus assigned to himas many groups of switches 9-10-13 (with their associate' contactbuttons) as there are operators, all of the switch arms -9-10-j13corresponding to a given subscriber, being desirably mounted upon ashaft 18 of a link; circuit motor 19 that is brought into operationunder conditions hereinafter to be set forth, when'the subscribersswitches 5`-6-11 have become connected with Vthe arms 9-10f-13corresponding to a free operator. Each subscribers line thus has a motor1 9 that. serves to operate the switches 9-10-13 corresponding tol allof the operators," it being only such switches, however, that areconnected with the switches 5-6-11 'that perform any function es aconsequence of their operation. The switches 91--101131 correspond toanother subscriber and extend to contact buttons similar' to contactbuttons 7-8-12 copcrating with another subscribers switch includingparts similar to parts 5-6-11. All of ,these arms 91-101-131 are adaptedfor simultaneous fifi operation by a -link circuit motor correspendingto the subscriber to whom the elements 91-101-131 belong. By apparatusto vbe specified, the switch elements 5+6-11 are brought into connectionwith the arms 9-10-L5 that correspond to an operator whois free to takework, the said apparatus enabling the said switch elements 5-G-11 topass by any arms 9-10-13 that are associated with the apparatus of anoccupied operator. in order that the parts 5-6-1l may be arrested intheir travel (their travel hai/"ing been commenced by apparatus to bespecified), the cord circuits or link-circuits jointly control 'andeil'ect a circuit conditionv "that will cause-the motor mechanismoperating the parts *5--6--11toi'ceasesuch opera.

tion when all ofthe link circuits that an operator is given to' use arenot in service, the f said link circuits effecting another circuitcondition when theyA are in use up to the capacity of the operator. v

Without at the present time describing the apparatus by which the resultpresentlyv to be stated is accomplished, I prefer to cause the linkcircuits belonging to each operator and the apparatus for the purposgoverned thereby, to place grounds upon t e contact buttons 20 when allof said link circuits are group of buttons 20 a grounded button 201ywith which the element 21' is normally engaged, so that the parts 5-6-11may be moved at once upon the initiation of a call.l

The wiping portion of the element 21 is broad enough to engage onebutton before leaving the preceding, for an obvious reason. There issuch a set of buttons 20 and a button 201 for each subscriber, eachbutton of each set being associated with apparatus at one operatorsposition, there thus being as many buttons in each set as there areoperators positions or as there are sections of board. The buttons ofthe different sets (corresponding to the different lines) that areassociated with the apparatus at oneI When a operators position, aremultipled together, y

as indicated in the lower left-hand and lower right-hand corner of thedrawing, so that any switch element corresponding to y element 21 ridingover a set of buttons corl responding to the buttons 20, by coming intocontact with the iirst button from which the ground has been removed,will cause the operation of the parts similar to parts 5--6-11 to cease.

I will later explain how the parts 9-10-13 willstop when they engagebuttons 1415-16 that correspond tol an idle link circuit, and will alsolater describe the calling signal that is then operated.

I will now describe the apparatus by which the operation of the elements5, 6, 11 and 21 is controlled.

A calling subscriber, as subscriber A, by

removing hisreceiver from its switch hook, establishes a circuit at theexchange which may be traced from the grounded armature 11, over thesnbscribers line, to`the contacts p,

' cannot be further moved thereby.

2-21, the line relay 22, to the grounded battery 23, whereby thearmature switches shown in association with said line relay areoperated.. One of said armature switches 24 thereupon establishes acircuit through a winding 25 ,of a corresponding subscri'bers motor,which circuit may be tracedfrom the ground at 201, the switch 21, theconductor 2 7 connecting said switch with Athe front contactof switch24, the lazy arm 28, between the bifurcations of which a projection ofthe armature 29 is located, the winding 25, to the battery 23. The enerization vof this magnet 25 is intermittently e ected by reason of theseparable relation of the lazy arm 28 and its contact, so that thearmature 29 is intermittently operated to engage the teeth 30mechanically. united with the switch parts 5--6-11-21. Thus, the firststep is the movement of the part 21 from thegrounded contact button 201into engagement with the next button. Now, if the operatorl with whoseapparatus the said next button is associated is not free, there willalso be a ground upon said next button, thereby still maintainingthecircuit through the magnet 25. If the neXt\ operator is fully occupied,the button 20 ycorrespondingl to her position or board section is alsogrounded and the movement of the parts 5-6'11-21 continued, thisoperation being carriedon until the brush element 21 comesinto contactwith a 'button20 that corresponds with a free operator, whereuponcircuit through the magnet 25 is etectively opened, by the removal ofthe ground from the corresponding contact buttons 20, so that theparts5-6-11-21 In the instance illustrated at the left of Fig. l, thevery first button 20 encountered by the switch part 21 is supposed to beassociated with an operator who is not fully occupied,

but who is free to put up more connections,

so that the circuit through the magnet 25-is opened to arrest the switchparts 5-6-11'- 21. The switch arms 9-10-13 that are thus ,connected withthe parts l5-6---11 as indicated, are tho switch arms that areassociated with the apparatus of the operator corresponding to thebutton 20 shown in conncction with the-element 21, whereupon the primemover 19 is brought into service to move the said switch parts 9-10-13to c0nnect the same with the'answering terminal buttons 14-15-16 thatmay be connected or associated with the link circuit of the selectedoperator that may be used in effecting connection between the callingand called subscribers, as l prefer an automatic connection between theanswering end of the link circuit" and the calling subscriber, thoughthat feature of my invention involving the automatic selection of theplaceat which the calling signal is to appear is in itself a veryimportant feature of the invention, particularly where the mechanismthat is to govern this automatic selection of suclrlocation is jointlycontrolled by the link circuits. The

motor that is employed for the operation of including the electro-magnetwinding of the element 31 may be traced from the grounded generator 33vto be employed for operating ,said magnet, which generator ispreferably a source of alternating current, to the back contact of anarmature switch 34, the armature switch 35 and its front contact, to thearmature switch 36 and its front contact, which is grounded. Thiscircuit is broken at 34, however, during the time circuit is establishedthrough the magnet 25 because the magnet -37 is included in circuitwithswitch 24, thereby removing the armature switch 34, preventing theclosure of the circuitV through the generator 33. This connection 34 isprovided because the magnet 38 is preferably employed. to operate theswitches 71-81 temporarily to disconnect the parts 5 6 from the callingsubscribers line, circuit being established through said magnet 38 bythearmature switch 39 engaging its front contact, the armature switch 40engaging its front grounded contact, the magnet 38, thegrounded battery23. It might be stated that Vthe armature switches 24-35-39 aregovernedby the' relay 22 and the armature switches 34-40 are governed bythe relay 37. When the circuit through magnet 37 is opened at 21,circuit through the elements 31-33 is established by the release o the.armature switch 34 that thereupon engages its back 4contact, saidcircuit continuing from said back contact, through the armature switches3LP-35, the front contact of armature switch 35, the armature switch 36,to the grounded contact of said latter armature switch. It is necessaryto maintain the armature switch 36 in engagement-*with its groundedcontact in the embodiment of the invention A illustrated, while themotor 19 is in operatiomin order that the ground at 36 may bennaintainedto continue the establishment of the circuit containing the generator33, to which end the back or normal contact of armature switch 40 isconnected with the switchv elornent 1l, which determines the location ofthe ground supplemental to the ground at the battery 23 toestablish'this circuit of said `magnet 38. By conditions hereinafter `tobe set forth, the contact buttons 12 connected with the apparatus at thediii'erent operators positions or board sections, have grounds placedupon the 'same through the intermediation of the switch elements 13,

the Contact buttons-16 engaging said .switch 38 is maintained, and whichmay readily be traced 'as hitherto indicated. As soon, however, as' theiirst idle link circuit or the button ,16 co1, sponding thereto, becomesassociated vwith "the arm 13, the ground is removed' from the element11, causing the deenergization 'of the magnet 38, thereby removing thearmature 3.6 from its grounded contact and opening the circuitcontaining the elements 31-33, so that the parts 9 10-13 remain in theposition .they were brought to when vthe switch arm 13 engaged thevbutton 16 vfrom which the ground had been removed because of the idlecondition of the link circuit associated with the said button 16 thusengaged. 'All of the operaa tors may be provided with the same number oflink circuits, but the number of those cire cuits that may be broughtinto service may be limited by providing artificial means for placinggrounds upon the buttons 16 or otherwise throwing the link circuits outof operative relation with the operating mechanism of the exchange,there being indicated in the embodiment of the invention shown, manuallyoperated switches 41 thatv may be moved into connection with groundedbuttons when the link circuits associated with said switch arms arethrown out of service. -When the arms 9-10 are arrested, conductors42-43 o'l'an idle link circuit belonging'to afreev operator, areconnected with the arms 9-10 and thereby with the buttons 7 8 and theswitch parts 5-6 engaging said buttons, so that the calling line isconnected with said link conductors 42- "3 1, the switch element 5, thebutton 7, the

traveling switch 9, the link conductor 42 {in this case the sleeve'strand of a cord circuit), the relay 48 (which becomes therebyenergized), to the grounded battery 23. The subscribers apparatus noweffects an opera.-

tion of the calling signal 44, because the aru -line of the callinmature 45 ofthe supervisory relay 46v of the calling end of the cord isnowumattracted, and because the relays 47-48 are energized, wherebycircuit may be traced :from4 the grounded terminal of the signal 44,preferably a small, lamp, through the armature switch 49, the armatureswitch 45, the arF mature switch 50, to the grounded battery 23, thissaine circuit including a relay 51 common to a plurality of circuitscontaining the signals 44 to operate a common signal The circuit throughthe relay 47 may be traced from its grounded terminal, over the linkconductor 43 (in this case the tip strand of a cord circuit), to abutton 15, ,the engaging arm 10, a button 8, the engaging switch element-6, thence by way of the armature sol switch 71 and its contact, overthe telephone l subscriber, the armature switch 81, the swltchl part 5andv engaging button 7, the switch arm 9.'and engaging button 14, thelink conductor42, to the battery 23 by way of the magnet 48.A rlhesupervising apparatus and the balance of the operators apparatusassociated witlfthe.

connectinfr end of the cord circuit are well understood to those skilledin the art and need not have further description, except that thearmature 45, When attracted upon the insertion of a connecting plugwithin a called subscribers jack, serves to ei'ace the callmg signal at44. The operation of the supervisory apparatus 53-54 and the sig-l nalssupplemental to the magnet 55 will also be well understood from theillustration without requiring further description.

In order that the link'circuit motors 19 may be prevented from stoppingthe arms 9-10-13 to connect the samewith a link circuit already inservice, the buttons 16- 161 coperating with the arms 13-131 aremultipled. In order that the arms 9-10 and 91-101 may be connected withany idle link circuit, the contact buttons 14-141 are vmultipled, as arealso the but-tons 15--151.

The ground is placed upon and removed from the buttons 16--161through-the agency of the switch element 11 and the button 12 engagingsaid element 11, which operation and attendant results will now be setforth.

The ground that is to be placed upon and removed from the contactbuttons 16--161 is indicated at the grounded terminal of the relay 56.When the switch arm 13r (or 131, etc.) 'has encountered a button 16 (or161, etc.) having no connecticnwith a ground, (the windings 25 and 37having been denergized as hitherto stated)l the energization of thecut-oii relay 3 is permitted due to the denergization of the magnet 38eiected relay 22 occasioned because of the attraction of the armature 21in series with said magnet 22, the ground at 56 is thereupon at once 130switch parts to their initial positions, a post.

placed in connection with the armature `switches 39440 and the switchelement l1,

the exchange, so that if a magnet 56 assoc i'.V ated with a busy cord isthrown into circuit with a magnet 38 of a calling line, said magnet 38may remainv operated without caus- 4 ing the operation of magnet 5'6. p

If the calling subscriber restores his telephone before the operator hasvinserted theA connecting plug 17, or if the operator has withdrawn thelplug 17 after a completed conversation between connected subscribers,the calling subscriber then also having re- Stored his receiver, saidconductor 57 will have its circuit vextended by Way of the armature 49,now released, the armature 45,

also released, the armature 50, still attracted, to the grounded battery23, whereupon the magnet 56 will become energized to attract itsarmature 'and effect the engagement 'of the catch 58 in electricalconnection with the armature of magnet 56 with the hook upon a groundeddetent .59 preparatory to effectling the 'disengagement of said detentfrom the rack 30, to permit the spring- 60 to restore the` elements5--6-11-21-39 to their normal positions. The actual disengage- `ment ofthe detent 59 is preferably effected by means of a fs ring 61 connectedwith Athe 56, to which end the cir- "gnet should be opened, in i;,traction may not overcome 1itl spring, the spring being bf? thearmature pivot and the armature ma cuit of said i] order that its theforce of upon one sidel pole of the lilla-.griet upon 'the other. The

spring 61 is-l'tef'mitted to operate because the magnet again includedin circuit, by reason ofltlre ground placed thereuponat 59, causing theoperation of the switches 71-81, and thereby the denergization ofthemagnet 48, Whose armature 5!)v is released to open thecircuitthrough.the magnet 56, whereuponthe spring 61 is free to effec-twithdrawal-of the detent 59, so that the restoring spring 60 may moveitsassoc-iate 62 engaging the lhook 58 when suchrestoration is'aboutco," pleted to etl'ect disengagementA between said catchI 58 and thesaid detent 59, placin i' this apparatus in position to take parti`effecting a new connection. 'Ihe circuit'forlthe' magnet 38 justmentioned may heltiraced from the ground Aat 59, the hook 581, thearmature of magnet 56,

vcalling subscriber havin the winding of magnet 38, to the groundedbattery 23. After the parts 58-59 are separated, tl is circuit isopened. In case the motor 25 should step the switch contacts 5-6-11-21overl their entire range without having effected connection of alink'circuit with the line terminals 5-6, I provide a means foreffectingthe restoration of said elements, to permit a reoperationthereof. To this end, I-,preferably provide a supplemental contactbutton 121- tha't is not con-, nected with any arm corresponding to arm13, but is connected by way of a switch 63 with the battery 23, wherebysaid battery `is connected with the switch element 11` when said elementis in contact with the button 121. VVhen'the element 11 is thusconnected with the battery 23, the circuit including said elementcontains the armature switch 40 (beca-use the element 21 is not inconnection with the grounded contact, the magnet 37 vthereby being inopen circuit)v and its normal contact, the armature switch 39 and itsback contact, and the magnet 56. The Y manipulated his switch hook tosecure this'result, thus momentarily causing aA denergization of theline relay 22 to permit of theengagement of the armature switch 39 withits. normal or back contactl the armature of magnet 56 yis thereuponoperated to engagevthe hook 58 with the detent 59, whereuponthe-circuitd including the magnet 56 is broken at `63 by the armature ofsaid magnet, whereupon the spring 61 may withdraw 'the detent 59 topermit the spring 60 to restore the switch parts.'

I have hitherto stated thatbefore a cord or link circuit is tobeautomatically selected,

a group ofcircuits belonging to a free operator is?" first tobeselected, this in the eine bodim'eint of the invention being describedthe b ittoris 20 and the conditions jointly iinposet yjupon each `of thesame by-its assoeiate liaviiu" been el'ec'ted'through the agencyl/ofgroup; of 'link or cord circuits, a grou! of occufl'iied cordsoccasionin'g ground upo [its huttin 20, whereas a groi'ipxif cords noltr'igether occupied will cause its button'Z( to be freie of ground,with the results hith, 'to

stated? cludirlg the apparatus operating'ungler the laws the Wheatstonebridge, The bridge ized inlay 64whose polarized armatura-is groun"` ed,such relay being common tripa groupiiof cord or link circuits and j oinly contro 'led in its-operation thereby. In`1 we operation ,of the,Wheatstone a'rrangcrnelzit more gilly tobe set .foi-th, said armature`iis maint ned in the position illustrated in tile ic i i drawi ig atthe left when all of the servi,

Thepreferred instriiul'ientality tlliat I emlxloy fr controlling the,applicatio 'dof nd to each button QQ-b'y 'its group of' `link orcordicircuits, is that` illustrated,A in'- of thi- Wheatstone 'circuitincludes'a polarablev link circuits of a given operatorare not in use,so that the conductor 65 terminating at one end' in a contact button 20and at the other end in a contact 'for the said armature, is under Asuchcondition free of ground connection, but when all of the serviceablecords are in use, the said armature 1s swung ,to itsxalternativeposition into six connections, sal 8, the resistance 70 is. y*

.correspondingly a justed to permitvthe in-.

engagement with its contact, the terminal of the conductor 65, so thatground is placedl upon the contact 2,0 corresponding to 'said group oflink circuits, forcing the switch l Aelements 5-6-'-],1'-,21V tocontinue their movementas hitherto set forth. The direcauV tion ofmovement ofthe Aarmature of relay '64 depends upon the direction' ofcurrent through ,said relay from the battery 23, this battery 23 beingconnected between two adf jacent sides-66-67 of the Vheatstone bridgeclusion of eight sections 71 abreast 'before the conductor 65A isgrounded throughl the armature of thefrelay 64.. As, soon as thepredetermined number of sections that mayv be' included abreast isdiminished, the vcuir:

rent 'through the winding of relay 64 is rel` ,versed to remove therelay armature 'from connection withthe condu'ctor 65. Arelay 7 3'belonging to'another group of link circuits is illustrated, thearmature thereof Il being shown applied to a conductor 74 (as containingthe fixed resistances. The other two sides'68--69 of" the VVheatstonebridge are grounded, and,'as' the battery 23 is grounded', the vWhcatstone bridge arrangeythat/is automatically adjustable through nientthat I have described is completed, for there is 'included in the sideG8 resistance the agency of' the link circuits, such adjustment beingeffected 'as said link circuits are put into and withdrawn from service,the other side 69 containing avv resistance 70 that y is to be adjustedmanually according tothe capacity o f the operator using the cordcircuits vassociated with the relay 64. The resistance of the side 68 ispreferably composed of a number of sections 71, each cord circuit of agroup having one such section. Y The relay 48 of each link'4 circuit hasan l armature switch 72 that engages a. grounded fcontact when operatedby said relay to include the corresponding resistance sections 7linground connection. The resistances, 71 ai'e thus connected in circuit astheir associate link circuits' are busy and are exeluded from circuitwhen .said circuits are 'restored to their normal or idle conditions.The .resistance 70 is adpistedby hand to through the rcla-y (S4 shall beso directed as to effect an application ofthe relay armature to theterminal of. conductor (35 asso-V ciated therewith. Each operator mayhave ten link circuits, but the resistancel may ,said called subscribersline.

the 4'serviceable link circuits corresponding to saidrela'y areoccupied),=sai'd'conductor being connected with a button 20 of-a group.

A non-numerical switch is one that does not operate in response to -aseries of im- .pulses' transmitted by a calling device, but4 4 yoperates in response to the transmission of an impulse or upon theclosure of a circuit, such-as. the closure of 'a subscribers substationcircuit.

What I claim as new v'andldesire to secure by United States LettersPatent is:

ondary switches to extend the subscribers l line toone of saidconnecting circuits, and means. for then extending the connection to v2.A telephone system'inclu'ding a Sub#A`VY scribe'rs telephone line,A afprimary switch for said line, a secondary switchaccessible to saidprimary switch, trunking means accessible to said secondary switch, andinechaf 'uism for said primary and secondary 'determine the time atwhich thef currentv switches responsive to the removal of a receiver atthe substation of said telephone "line to connect said telephone linewith Vsaid be so adjusted that the. moment six,for'

example, of the resistance sections 7l are connected to ground,the-armature of relay 64 will be connected with conductor 65, so thatthe selecting mechanism of the subscriber calling will pass the button2O connected with conductor G5 thus grounded, until the element 21 ofsaid selecting mechanism will .engage a button 2() from' which theground has been removed. Thus` the operator having the relay 64 cannotattend to more than six connections at a time. if

trunking means. 115 A telephone system including a calling and a calledsubscribei"s line, connecting circuits, individual primary andnon-numeri cal ,secondary -trun king switches, a line relay individualto the calling Subscribers line 126 for.. initiating the operation ofone of said primary and one ot' said secondary switches forconi'iecting-said calling subscribers line Yto an idlcone of saidconnecting circuits,

and means for then extending the connection to said called subscribel"sline'.

' -4f. A telephonev system including a calling and a called subscribersline, trunk lines,

. non-numerical primary and secondary trunkthe capacit-y 'of theoperator is greater than.'

ing switches, the primary switches being in- 130 so- 1. A ytelephonesystem including a calling l f Ma" dividual to the subscribers lines, aline relay individual to the calling subscribers line and controlledover the two sides of said line 1n series for causing the successiveoper- 5 ation of one of said primary and one of said' secondary switchesto extend a call from the calling subscribers line to an idle one ofsaid trunk circuits, and means for then connecting with and signalingthe called'subscribers line.

5. A telephone system including subscribers telephone lines, grouiis ofprimary switches for said lines, secondary switches accessible to saidprimary switches, a group Aof y connecting circuits accessible to saidsecondai'y switches, and lmeans controlled over tlietwo sides of acalling'line in series to operate one of said primary switches and oneot said secondary switches to connect to one of said v connectingcircuits, and operator controlled means for extending connection fromsaid connecting circuit to a called one of said lines. M

6. The combination with a selector carrying-groups ot' line terminals,of a coperating movable contact 'therefor adapted to' test said lilies-by groups', and nie'ai'is, actuated 1n case all the lines in a testedgroupare unselectable, for advancing,r said movable con- 0 tact in asiiiglestep to the next group.

7; The combination with groups of lines, of a selector carryingterminals for said groups, a test contact foreach group of lineterminals, a source of current associated with.

. eacliwgroup,'a. conductor connecting said sourde with the test contactof each group, and irieans for Vary-nig' the continuity ot' saidconductor according to the seleetability or non-'selei'll'ability-of theline tei'iiiinals int'liat ,s0 'group H..I`he minliination' with anumber of groups ot'k truuk line teriiiiiials,.ol selective apparatust'oi connecting therewith adapted to test said groups ot tei-initialsone after v 45. the other to'select a group containiiigan idle trunkline. i I

it. 'l`he coinbiiiatiijin with groups of trunk lines, ot a .selectorcarrying teiiiilnals tor saidgi-oups` a test contact t'or eachgroup'ot'I trunk linel terminals, a sourceyot busy current associ-ated.with4 each group, and a conductor connecting said source willi the testcontact olf` said group, the -ontiiiuityot' sau-l conduit.--`

' tor heilig completed when all the lilies in said-group are busy.

10. ',l`he"coiiibination with a selector carry-- ing groups ot truiikline teriiiiii-als, of a contart ai'in tl'ieret'or adapted to test saidti'iiiilc lines h e'rou is and iiieans actuated iii-case y all the truuklines iii a testedjgioi-ip are i busy, for,a'di'aiiciiigr said ariii iiiitsiiigle step to the next group.

ll. The coiiibinat ion with a Selector carrying groups ot lineteiiiiiiials,ol a cooperating nio vable contact therefor adaptedto testsaid rality offsubscribcrs #telephone lines,

-iutoi'iiatic triinlnng switch. individual t0. ,each of said subscriberslines, secondary -said lines to an idle one ai said trunk lines bygroups, and means, actuated incase.

all the lines in a tested group are unselectable, for advancin,9I saidmovable contact in a single step to the next group.

12. A telephoi'ie system including a subscribers telephone line, anautomatic switch individual thereto,- a' secondary automatic trunkingswitch accessible to'said first auto" matic switch, trunk linesaccessible toA said secondary automatiqswitch, and ,means controlled bythe calling subscriberlover the two sides of the subscriber-slime:inseries for f operating said automatic iswitches"` to extend alconnection from sai Subscifibers line to an idle one of said trunkcircuits."`

-18.VA telephone system lincluding a plurality-ot' subscriberstelephoneJ lines, autoiiiatic trunking switches-one for each of Saidlines, secondary `tf1-linking switches accessible ,tol isaid firsttrunkmg switches,

oups. of

link circuits accessible to said secondary4 switches, and meanscontrolled by a calling one of saidsubseribers over the two sides'ofthe' subscribers line 1n lseries for operating the switch individual tothe subscribersline l and one of said secondary trunking switches-fo'connect said subscribers line to an idle.

one of. said link circuits.

14.l A ,telephone systeiii including a plulrality ot' subscriberstelephone lines, aut

matic trunking switches one'for each said lines, secondary trunki-ngswitches accessible to said first. trunking switches,

circuits,'and iiieans for extending a con-- iiection from saidliukcircuit to' a. called one ot' said subscribers lines. 15. telephonesystem including a plutrunkiug switches. accessible to said viirsttruiili'iiig switches, trunk circuitslaccessible to saidsecondary.trunking switches, subscriber controlled iiieans forsuccessively operating his individual trunk sii'itcli.aitd

one of said .secondary truiil-:ing switches to extend a connectionfroiii the calling one of circuits, and iiieans for then completing thelconnection to a ycalled one of said lines.

toiiiatic truiikiiig switch'individual to said subseriliers line, asecondary Inon nuiiierical lt. A telephone systeiii includinga sub-`scrilicr`s telephone line, a iioii-iiiiiiierical autruiikiii'url switchaccessil'ile toA said tirstl truiiking switch, wipers for said secondaryswitclifgroups of trunk circuits accessible ing and a called subscriberstelephone line,

17. A telephone system including a .sub-

Vscribers telephone ,line a lnon-numerical automatic trunking l'switchindividual to said subscribers line, a secondary non-numerical trunkingswitch accessible to said first trunking switch, wipers or s aidsecondary Switch, groups of trunk circuits accessible to the wipers ofsaid secondary? switch, and subscriber controlled means foipsuccessively operating said switches to eX- tend av connection from saidsubscribers line to an idle one of said trunking circuits, said meansbeing controlled over two sides of the subscribers line 4in series.

18. A telephone system including a subscribers telephone line, anlindividual nonnumerical trunking switch therefor, a second-arynon-numerical trunking switch terminating in bank contacts of said firsttrunking switch, a plurality of trunk circuits terminating in bankcontacts of said secondary switch, and subscriber controlled means-foroperating said switches to extend a connection from said. subscribersline to an idle one of `said trunk circuits.

19,. vA telephone system including a calla non-numerical trunking switchindividual to said callinggsubscribers line, a secondary non-numericaltrunking switch accessible to said -first trunking switch, trunk linesaccessible to said secondary Switch, ,subscriber controlled means forsuccessively operating said switches to extend a connection from thecalling subscri'bers line to. an idle one of said trunk circuits, andmeans for extending, aconnection from the selected trunk circuit to thesaid called subscribers line.-

20. 'A telephone system including aplurality of,subscribe'rs telephonelines, a nonnumerical progressively movable tr'unking switch for each ofsaid subscribersftelephone lines, secondary non-numerical trunkingswitches't'erminating in bank cor'itacts of said iirst trunkingswitches, and accessi ,ble "thereto,.trunk circuits terminatingl in ,has

bank contacts of said secondary trunkingswitches and accessible thereto,and means controlled by a calling one ofgsaid sub,

scribersfor,opepating his individual trunk-- ing switch and one of saidsecondary switches to extend aconnection from the subscribers telephoneline to an idleoiie oty said trunk' circuits. y ,i

21. A telephone system including'a plurality of subscribers 'telephone'lines, a non-numerical progressively mova'bl'e trunk-` ing switch forcach of said subscribers telefy phonelines, secondary non-numericaltrunky l ing a group of conductors, groups of autoing switchesterminating infbank contacts j ing. algroup of said first trunking.switches and accessible thereto, trunk circuits terminating in bankcontacts of said Ysecondary trunking switches and accessible thereto',means controlled by a calling oneJof said subscribers for operating hisindividual triinking-switch and one of said secondary switches to'extend v l I -a connection from the subscribers telephone line to `anidle one of said trunk circuits, and means for then extending theconnection from the selected trunk circuit to a called one ofsaidsubscribers lines 22. A telephone system including a tele phone line,selective switch mechanism, a A

plurality of operators cord circuits having terminals associated withsaid switch mechanism arranged in groups, means outside of said switchmechanism for rendering some of said groups busy, means for operating,said switchmeclianism on initiation of'a call. over -said telephoneline` whereby said.

switch mechanism automatically tests said cord circuits by groupsavoiding -busy groups,and means for causing said switch matic switchpassive contac.ts,.each group" having contacts forming terminals of.said .l conductora, means associatedVwith each ygroup ofpassive-contacts for automatically selecting the passive contact ofa'n'idle one of said conductors, means for selecting said group ofconductors, and means responsive tothe selectionof;v all theconductorsin the lgroup to control r,said

24'. -Atelephone exc ofconductors,l groups of automatic switc i'ngcontacts forming',t terminals of said conductors, means associated witheach group of passive 'contacts for automatically selecting. fthepassive contact of an idle on'e'of` said conductors, meansfor selectingsaid group of conductors, and means responsive to the to cau'setheselecting means to move by lthat group selecting means; lange systemcomprisv y i passivecontacts, each group hav- "selection of all theconductors in the 'group iis ing a group of conductors, groivipsofautohaving contacts forming terminals of said conductors,meanslg'associated with each ,group of passive contacts forautomatically selecting the passive contact of an .idle one. of rsaidconductor-skincans for selecting said:

'matic switch passive contacts, eaclngroup j 'piaci V for said' groupselecting means, an electro magnet for each conductor, means forenergizin each conductors magnet upon the selection of that conductor,and means responsive to the energization vof the magnets of all theconductors to actuate said switch.

QXL-In a telephone system, a subscribers ating magnet insaid switchnormally connected to said dine, a cut-off relay, and means forenergizing 'said cut-off relay to disconnect said operating magnet fromthe 'line when said line is calling or is being line, an automaticswitch connected to'said line provided with a Contact maker ,capable ofassuming a plurality of selective positions, trunk lines for selectionby said automatic switch, a second subscribers line, means includingsaid automatic switch for extending a call from said first to saidsecond subscribers line means for 'eXtendin a call from said second tosaid rst subscribers line, operating means for said switch bridgedacross said line, and a magnet or'disconnecting said operating meansfrom across the line when said first connection is established, saidmagnet also being operable to disconnect said operating means fromacross'the line when said second connection is established. A

28, A telephone system ineluding'a subscribers line, an automatic switchindividual, thereto, a second subscribers llne, means 1n' cluding saidindividual switch for extending a connection from said-first subscribersiine to said second subscribers line, means Jfor extending a connection:from said sec'- ond subscribers line to said first subscribers line, anoperating relay for said switch connected to said Irst line, and a cut-orelay for disconnecting said operating relay from said first subscribersline when said switchis used to extend the connection to the secondsubscribers line, said cut-0E relay also being operable to disconnectsaid operating relay from said subscribers line when the secondsubscribers line is connected to the said i'irst subscribers line.

29. in a telephone system, a subscribers line, a progressively movablenon-numerical switch individual to said line for extending connectiontherefrom, means for establishing a connection to said line, anoperscribers line,

called. y

30. A telephone system including a suba progressively movable switchindividual to said line, means for extending a connection from saidsubscribers lineincluding said switch, an operating magnet for saidswitch normally connected to said subscribers line, a cut-off relay,means ,for energizing said cut-ofi' relay to disconnect said operatingmagnet from the sub'sc'ribers line when said switchl is operated forcalling purposes, and means for ener izingfsaid cut-od relay todisconnect sai operating ma et from the subscribers line when saincalled line.

31. A telephone line having before it mul-` tiple terminals of linkcircuits,- said link circuits having before them multiple termi- Vnalsof other circuits, and non-numerical switch mechanism for said lines andlink circuits adapted to extend said line by means of a selected idlelink circuit terminal and a selected idle terminal of one of said othercircuits.

32. A. telephone system including a subscribers telephone line, aprimary .switch for said line, a secondary switch accessibleto saidprimary switch, o erators answering means accessible to sai secondaryswitch, and mechanism for said primary and secondary switches responsiveto the removal of a receiver at the substation of said telephone line`to connect said telephone line with said answering means.

33. A telephone line and automatic switch.- ing means provided with acontact maker capable of assuming a plurality' of selective positionsindividual to said line, an electromagnet individual to said telephoneline' operating responsive to a control over said V,line to disconnectsaid automatic switch,

and means for controlling said magnet to disconnect said automaticswitch when connection is made to -said line as va called line. Signedby me at Scarsdale, in the county of Westchester, and State of New York,this 16th day of January, 1918.

. FRANCIS W. DUNBAR.

line is used as av

